Comparative settlement depths of Mytilus edulis C. Linnaeus, 1758 and M. Trossulus Gould, 1850: II. Field observations

Controlled mesocosm experiments using larvae of Mytilus edulis and M. trossulus have shown that the two species have different settlement patterns with respect to depth, and that the presence of a thermocline can modify the depth distribution. A field program was conducted over 3 y at one site, and at two sites during the final year to determine the settlement patterns of these species in the wild. In all analyses, there was a greater percentage of M. edulis postlarvae settling at 5 m than of M. trossulus. In addition to opening up certain ecological questions, these results show promise for direct application to husbandry practices at mussel farms having both species, where preferential collection of the M. edulis is desirable.